The present invention relates to a rotary laser irradiating system, by which it is possible to form a reference point, a reference line and or a reference plane for measurement by irradiating a laser beam or by performing reciprocal scanning or by rotating a laser beam, and in particular to a rotary laser irradiating system which can form, in addition to a horizontal reference plane, an arbitrary tilt setting plane tilted at a predetermined angle with respect to the horizontal reference plane.
To obtain a horizontal reference level for wide range, a rotary laser irradiating system is used instead of an optical leveling device.
In recent years, the use of the rotary laser irradiating system has been widely propagated for measurement in a height direction, in particular, in case a line, a plane, etc. are formed according to a reference height. The rotary laser irradiating system of this type is designed in such manner that a laser beam is irradiated in a horizontal direction while it is rotated or it is irradiated for reciprocal scanning or it is stopped to form a rotary reference plane, or to form a partial reference line, or a reference plane, and further, a reference line and a reference point.
For example, the system of this type is used to form a reference horizontal line for positioning of a window frame in interior construction of a building, or to form a reference horizontal plane when soil filling is performed in civil engineering and a graded soil surface is formed. In some of the rotary laser irradiating systems of this type, a reference plane tilted in a direction or in two directions can be formed, and it is now possible to form a tilted reference plane easily.
As an example of a conventional type rotary laser irradiating system, brief description will be given below on the rotary laser irradiating system disclosed in JP-A-6-26861 referring to FIG. 6.
At the center of the upper surface of a casing 1, a recessed portion 2 in truncated conical shape is formed. A laser projector 3 penetrates vertically through the center of the recessed portion 2 and is tiltably supported on the recessed portion 2 via a spherical seat 4. The head of the laser projector 3 is provided with a pentagonal prism 9 and serves as a rotator 5, which can be rotated freely. The rotator 5 is rotated by a scanning motor 6 via a driving gear 7 and a scanning gear 8.
On the circumference of the laser projector 3, two sets of tilting mechanisms 10 (only one of them is shown in the figure) is provided. The tilting mechanism 10 comprises a tilting motor 11, a tilting screw 12, and a tilting nut 13. The tilting motor 11 rotates the tilting screw 12 via a driving gear 14 and a tilting gear 15, and the tilting nut 13 is connected with the laser projector 3 via a tilting arm 16. Driven by the tilting motor 11, the tilting nut 13 is moved up or down, and the laser projector 3 is tilted by upward or downward movement of the tilting nut 13.
On the middle portion of the laser projector 3, there are provided a fixed tilt sensor 18 in parallel to the tilting arm 16 and a fixed tilt sensor 19 placed perpendicularly to the fixed tilt sensor 18. On the lower end of the laser projector 3, a flange 20 is fixed. On a pivot pin 21 erected on the flange 20, an L-shaped tilting base 22 is supported at one point on the corner. Two ends of the tilting base 22 at positions perpendicularly to each other are connected to two sets of tilt setting mechanisms 25 (only one of them is shown in the figure) respectively. On the tilting base 22, an angle setting tilt sensor 29 is arranged in the same direction as the fixed tilt sensor 18, and an angle setting tilt sensor 30 is arranged in the same direction as the fixed tilt sensor 19.
The tilt setting mechanism 25 comprises a tilt angle setting motor 26, a tilt setting screw 27 rotated by the tilt angle setting motor 26, and a nut block 28 screwed on the tilt setting screw 27, and one end of the tilting base 22 is engaged with the nut block 28. By driving the tilt angle setting motor 26, the nut block is moved up or down via the tilt setting screw 27, and the tilting base 22 is tilted.
Inside the laser projector 3, there are provided a laser emitter (not shown) and a projection optical system (not shown), which comprises components such as collimator lens, which turns the laser beam emitted from the laser emitter to parallel beams. The laser beam from the projection optical system is deflected in a horizontal direction by the pentagonal prism 9 and is irradiated through a projection window 31.
On the upper surface of the rotary laser irradiating system, a sight (foresight/backsight) 32 is provided. Using this sight 32, it is possible to perform collimation in two directions, i.e. a tilting direction by the tilting mechanism 10, and also another tilting direction perpendicular to the above tilting direction by another tilting mechanism (not shown).
Description will be given now on a procedure to form a tilting reference plane by the above rotary laser irradiating system referring to FIG. 7.
The rotary laser irradiating system 35 is installed on a tripod 33 erected at the reference position. At the position of a target in a tilting direction, a collimation target 36 is erected (FIG. 7(A)). When a laser beam irradiating from the rotary laser irradiating system 35 is projected in the reference direction, i.e. when the projecting direction of the laser beam is consistent with a tilting direction of the laser projector 3 tilted by the tilting mechanism 10 and the fixed tilt sensors 18 and 19 both indicate a horizontal direction, fixing screws of the tripod 33 are loosened so that main unit of the rotary laser irradiating system 35 can be rotated with respect to the tripod 33. While collimation is performed through the sight 32, the rotary laser irradiating system 35 is rotated. The collimation target 36 is collimated through the sight 32 and the projecting direction is aligned with the collimation target 36 (FIGS. 7(B) and (C)). Next, a tilt angle .theta. is set, and a laser beam is projected, and a reference line is formed (FIG. 7(D)).
The tilt angle is set by the tilt setting mechanism 25. When the fixed tilt sensors 18 and 19 indicate a horizontal direction, the tilt angle setting motor 26 is driven to rotate the tilt setting screw 27. Then, the nut block 28 is moved up or down, and the tilting base 22 is tilted at the same angle as the setting angle .theta., but in a direction reverse to that of the setting angle. The tilt angle of the tilting base 22 is detected by an encoder, etc. connected to the tilt angle setting motor 26.
Next, the laser projector 3 is tilted in the tilting direction by the tilting mechanism 10. When the tilting base 22 detects a horizontal direction, a tilt angle is the setting tilt angle of the laser projector 3. When the tilt angle of the laser projector 3 is at the preset angle, a laser beam is projected in a horizontal direction from the laser projector 3 through the pentagonal prism 9, and the rotator 5 is rotated, or reciprocal scanning is performed in the range of a desired angle. Then, a tilted reference plane is formed.
As described above, in the conventional type rotary laser irradiating system, the tilt angle is electrically detected by the tilt sensor and is electrically set by the tilting mechanism 10, and it is possible to perform the setting at high accuracy. However, the tilting direction is determined by the sight 32. Originally, collimation by sight can be performed without requiring high-grade technique. Because sophisticated technique is not needed, the accuracy of collimation is not very high. Further, there is also man-made error, and the decrease of accuracy is unavoidable. In civil engineering work in the past, high accuracy has not been required, and collimation by sight has been satisfactory for the purpose, but in the almost completely mechanized civil engineering work in recent years, higher accuracy is required, and the accuracy of collimation has become an important issue. Further, performance characteristics of the rotary laser irradiating system itself has been improved, and when it is used for the surveying for remote site, collimation itself has become difficult using the sight as described above.
In some cases, a collimating telescope is used instead of the foresight/backsight, but it is not possible to collimate in two directions perpendicular to each other as in the case of the foresight/backsight. In case it is wanted to collimate in two directions, the collimating telescope has to be re-arranged each time. This means much labor and time for the work and hence poor working efficiency. Accuracy is an issue in re-arranging the collimating telescope.